A closer examination of the ‘abundant centre’ hypothesis for reef fishes

Abstract

Aim: The 'abundant centre' hypothesis states that species are more abundant at the centre of their range. However, several recent large-scale studies have failed to find evidence for such a pattern. Here we used extensive global data of reef fishes to test the 'abundant centre' pattern, and to examine variation in the abundance patterns across species using life history and ecological traits. Location: Marine habitat at a global extent: from Indo-Pacific to Atlantic reefs. Methods: We used underwater visual estimates of fish abundance, containing 22,963 transects and 1,215 species. For each species we calculated the slope between abundance and distance to the range centre, with the range centre estimated using four different methods. We tested whether abundance patterns differ between the range core and margins using segmented regression. Meta-analytic methods were used to synthesize results across species, and to test whether species traits can explain variation in the fit to the pattern among species. Results: The method used to define the range centre had a large effect on the results. Nevertheless, in all cases we found large variation between species. Results of | 2195 YANCOVITCH SHALOM eT AL.

A quantitative review of abundance-based species distribution models

“…Our finding that modelling abundance directly was better than an indirect approach (i.e., comparing our abundance-absence models to two-stage models) for more than 80% of species indicates that spatial abundance and occurrence patterns are somewhat mismatched, or at least not always congruent (although it is challenging to completely disentangle abundance from occurrence, and vice versa). Mismatches arise from different ecological controls of abundance and occurrence, such as different demographic rates controlling each to different extents (McGill 2012, Johnston et al 2015, Acevedo et al 2017, Dallas and Santini 2020, Schulz et al 2020, Yancovitch et al 2020, Bohner and Diez 2020). Understanding such mismatches offers an important avenue for better understanding range and abundance shifts under climate change (Geppert et al 2020) and potentially guiding spatial management and conservation.…”

Patterns of taxonomic and functional diversity in the global cleaner reef fish fauna

“…In the last decades, we have begun to better understand the global patterns and drivers of the distribution of richness and abundance of reef fishes, as well as to identify the processes that modulate them (Barneche et al, 2019; Bellwood & Meyer, 2009; Parravicini et al, 2013; Yancovitch Shalom et al, 2020). For instance, hotspots of both richness and abundance of reef fishes occur in the Indo‐Australian Archipelago and the Caribbean (Bellwood & Meyer, 2009; Floeter et al, 2008; Yancovitch Shalom et al, 2020). Historical (Pellissier et al, 2014), environmental (Barneche et al, 2016), geographical (Kulbicki et al, 2015; Parravicini et al, 2013) and physiological (Barneche et al, 2016) processes have been proposed as mechanisms that explain these patterns.…”

“…In the last decades, we have begun to better understand the global patterns and drivers of the distribution of richness and abundance of reef fishes, as well as to identify the processes that modulate them (Barneche et al, 2019;Bellwood & Meyer, 2009;Parravicini et al, 2013;Yancovitch Shalom et al, 2020). For instance, hotspots of both richness and abundance of reef fishes occur in the Indo-Australian Archipelago and the Caribbean (Bellwood & Meyer, 2009;Floeter et al, 2008;Yancovitch Shalom et al, 2020).…”

Using a robust multi‐settings inference framework on published datasets still reveals limited support for the abundant centre hypothesis: More testing needed on other datasets

“…Depending on the factor, different shapes, both concave and convex, can be expected. To date, few studies (Dallas et al., 2017; Osorio‐Olvera et al., 2020) have considered the potential for a nonlinear distance–abundance relationship and most of them have used rank correlations (Spearman; but see Yancovitch Shalom et al., 2020), a measure that provides no information regarding the shape of the relationship.…”